'''Chemical Engineering Design Library (ChEDL). Utilities for process modeling.
Copyright (C) 2016, 2017, 2018, 2019, 2020 Caleb Bell <Caleb.Andrew.Bell@gmail.com>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
This module contains implementations of :obj:`TPDependentProperty <thermo.utils.TPDependentProperty>`
representing liquid and vapor viscosity. A variety of estimation
and data methods are available as included in the `chemicals` library.
Additionally liquid and vapor mixture viscosity predictor objects
are implemented subclassing :obj:`MixtureProperty <thermo.utils.MixtureProperty>`.
For reporting bugs, adding feature requests, or submitting pull requests,
please use the `GitHub issue tracker <https://github.com/CalebBell/thermo/>`_.
.. contents:: :local:
Pure Liquid Viscosity
=====================
.. autoclass:: ViscosityLiquid
:members: calculate, calculate_P, test_method_validity, test_method_validity_P,
name, property_max, property_min,
units, Tmin, Tmax, ranked_methods, ranked_methods_P
:undoc-members:
:show-inheritance:
:exclude-members:
.. autodata:: viscosity_liquid_methods
.. autodata:: viscosity_liquid_methods_P
Pure Gas Viscosity
==================
.. autoclass:: ViscosityGas
:members: calculate, calculate_P, test_method_validity, test_method_validity_P,
name, property_max, property_min,
units, Tmin, Tmax, ranked_methods, ranked_methods_P
:undoc-members:
:show-inheritance:
:exclude-members:
.. autodata:: viscosity_gas_methods
.. autodata:: viscosity_gas_methods_P
Mixture Liquid Viscosity
========================
.. autoclass:: ViscosityLiquidMixture
:members: calculate, test_method_validity,
name, property_max, property_min,
units, Tmin, Tmax, ranked_methods
:undoc-members:
:show-inheritance:
:exclude-members:
.. autodata:: viscosity_liquid_mixture_methods
Mixture Gas Viscosity
=====================
.. autoclass:: ViscosityGasMixture
:members: calculate, test_method_validity,
name, property_max, property_min,
units, Tmin, Tmax, ranked_methods
:undoc-members:
:show-inheritance:
:exclude-members:
.. autodata:: viscosity_gas_mixture_methods
'''
__all__ = ['viscosity_liquid_methods', 'viscosity_liquid_methods_P',
'ViscosityLiquid', 'ViscosityGas', 'viscosity_gas_methods',
'viscosity_gas_methods_P', 'ViscosityLiquidMixture',
'ViscosityGasMixture', 'viscosity_liquid_mixture_methods',
'viscosity_gas_mixture_methods',
'MIXING_LOG_MOLAR', 'MIXING_LOG_MASS',
'BROKAW', 'HERNING_ZIPPERER', 'WILKE',
'DUTT_PRASAD', 'VISWANATH_NATARAJAN_3', 'VISWANATH_NATARAJAN_2',
'VISWANATH_NATARAJAN_2E', 'LETSOU_STIEL', 'PRZEDZIECKI_SRIDHAR',
'LUCAS', 'GHARAGHEIZI', 'YOON_THODOS', 'STIEL_THODOS', 'LUCAS_GAS']
from chemicals import miscdata, viscosity
from chemicals.dippr import EQ101, EQ102
from chemicals.identifiers import CAS_to_int
from chemicals.miscdata import JOBACK, lookup_VDI_tabular_data
from chemicals.utils import mixing_simple, none_and_length_check
from chemicals.viscosity import (
PPDS9,
Brokaw,
Herning_Zipperer,
Letsou_Stiel,
Lucas,
Lucas_gas,
Przedziecki_Sridhar,
Stiel_Thodos,
Viswanath_Natarajan_2,
Viswanath_Natarajan_2_exponential,
Viswanath_Natarajan_3,
Wilke_prefactored,
Wilke_prefactors,
Yoon_Thodos,
dPPDS9_dT,
viscosity_gas_Gharagheizi,
)
from fluids.numerics import brenth, exp, horner, isinf, isnan, log, trunc_log
from thermo import electrochem
from thermo.coolprop import CoolProp_failing_PT_flashes, CoolProp_T_dependent_property, PhaseSI, PropsSI, coolprop_dict, coolprop_fluids, has_CoolProp
from thermo.electrochem import Laliberte_viscosity
from thermo.utils import (COOLPROP, DIPPR_PERRY_8E, LINEAR, NEGLECT_P, REFPROP_FIT, VDI_PPDS, VDI_TABULAR,
MIXING_LOG_MOLAR, MIXING_LOG_MASS, MixtureProperty, TPDependentProperty)
from thermo.vapor_pressure import VaporPressure
from thermo.volume import VolumeGas, VolumeLiquid
DUTT_PRASAD = 'DUTT_PRASAD'
VISWANATH_NATARAJAN_3 = 'VISWANATH_NATARAJAN_3'
VISWANATH_NATARAJAN_2 = 'VISWANATH_NATARAJAN_2'
VISWANATH_NATARAJAN_2E = 'VISWANATH_NATARAJAN_2E'
LETSOU_STIEL = 'LETSOU_STIEL'
PRZEDZIECKI_SRIDHAR = 'PRZEDZIECKI_SRIDHAR'
LUCAS = 'LUCAS'
viscosity_liquid_methods = [REFPROP_FIT, COOLPROP, DIPPR_PERRY_8E, VDI_PPDS, DUTT_PRASAD, VISWANATH_NATARAJAN_3,
VISWANATH_NATARAJAN_2, VISWANATH_NATARAJAN_2E,
VDI_TABULAR, LETSOU_STIEL, JOBACK, PRZEDZIECKI_SRIDHAR]
"""Holds all low-pressure methods available for the ViscosityLiquid class, for
use in iterating over them."""
viscosity_liquid_methods_P = [COOLPROP, LUCAS, NEGLECT_P]
"""Holds all high-pressure methods available for the ViscosityLiquid class, for
use in iterating over them."""
[docs]class ViscosityLiquid(TPDependentProperty):
r'''Class for dealing with liquid viscosity as a function of
temperature and pressure.
For low-pressure (at 1 atm while under the vapor pressure; along the
saturation line otherwise) liquids, there are six coefficient-based methods
from three data sources, one source of tabular information, two
corresponding-states estimators, one group contribution method, and the
external library CoolProp.
For high-pressure liquids (also, <1 atm liquids), there is one
corresponding-states estimator, and the external library CoolProp.
Parameters
----------
CASRN : str, optional
The CAS number of the chemical
MW : float, optional
Molecular weight, [g/mol]
Tm : float, optional
Melting point, [K]
Tc : float, optional
Critical temperature, [K]
Pc : float, optional
Critical pressure, [Pa]
Vc : float, optional
Critical volume, [m^3/mol]
omega : float, optional
Acentric factor, [-]
Psat : float or callable, optional
Vapor pressure at a given temperature or callable for the same, [Pa]
Vml : float or callable, optional
Liquid molar volume at a given temperature and pressure or callable
for the same, [m^3/mol]
load_data : bool, optional
If False, do not load property coefficients from data sources in files
[-]
extrapolation : str or None
None to not extrapolate; see
:obj:`TDependentProperty <thermo.utils.TDependentProperty>`
for a full list of all options, [-]
method : str or None, optional
If specified, use this method by default and do not use the ranked
sorting; an exception is raised if this is not a valid method for the
provided inputs, [-]
Notes
-----
To iterate over all methods, use the lists stored in
:obj:`viscosity_liquid_methods` and :obj:`viscosity_liquid_methods_P` for
low and high pressure methods respectively.
Low pressure methods:
**DUTT_PRASAD**:
A simple function as expressed in [1]_, with data available for
100 fluids. Temperature limits are available for all fluids. See
:obj:`chemicals.viscosity.Viswanath_Natarajan_3` for details.
**VISWANATH_NATARAJAN_3**:
A simple function as expressed in [1]_, with data available for
432 fluids. Temperature limits are available for all fluids. See
:obj:`chemicals.viscosity.Viswanath_Natarajan_3` for details.
**VISWANATH_NATARAJAN_2**:
A simple function as expressed in [1]_, with data available for
135 fluids. Temperature limits are available for all fluids. See
:obj:`chemicals.viscosity.Viswanath_Natarajan_2` for details.
**VISWANATH_NATARAJAN_2E**:
A simple function as expressed in [1]_, with data available for
14 fluids. Temperature limits are available for all fluids. See
:obj:`chemicals.viscosity.Viswanath_Natarajan_2_exponential` for details.
**DIPPR_PERRY_8E**:
A collection of 337 coefficient sets from the DIPPR database published
openly in [4]_. Provides temperature limits for all its fluids.
:obj:`EQ101 <chemicals.dippr.EQ101>` is used for its fluids.
**LETSOU_STIEL**:
CSP method, described in :obj:`chemicals.viscosity.Letsou_Stiel`.
**PRZEDZIECKI_SRIDHAR**:
CSP method, described in :obj:`chemicals.viscosity.Przedziecki_Sridhar`.
**COOLPROP**:
CoolProp external library; with select fluids from its library.
Range is limited to that of the equations of state it uses, as
described in [2]_. Very slow.
**VDI_TABULAR**:
Tabular data in [3]_ along the saturation curve; interpolation is as
set by the user or the default.
**VDI_PPDS**:
Coefficients for a equation form developed by the PPDS, published
openly in [3]_. Provides no temperature limits, but has been designed
for extrapolation. Extrapolated to low temperatures it provides a
smooth exponential increase. However, for some chemicals such as
glycerol, extrapolated to higher temperatures viscosity is predicted
to increase above a certain point.
**JOBACK**:
An estimation method for organic substances in [5]_; this also requires
molecular weight as an input.
**REFPROP_FIT**:
A series of higher-order polynomial fits to the calculated results from
the equations implemented in REFPROP.
High pressure methods:
**LUCAS**:
CSP method, described in :obj:`chemicals.viscosity.Lucas`. Calculates a
low-pressure liquid viscosity as its input.
**COOLPROP**:
CoolProp external library; with select fluids from its library.
Range is limited to that of the equations of state it uses, as
described in [2]_. Very slow, but unparalled in accuracy for pressure
dependence.
A minimum viscosity value of 1e-5 Pa*s is set according to [4]_.
This is also just above the lowest experimental values of viscosity of
helium, 9.4e-6 Pa*s. This excludes the behavior of superfluids,
and also systems where the mean free path between moleules approaches
the geometry of the system and then the viscosity is geometry-dependent.
See Also
--------
chemicals.viscosity.Viswanath_Natarajan_3
chemicals.viscosity.Viswanath_Natarajan_2
chemicals.viscosity.Viswanath_Natarajan_2_exponential
chemicals.viscosity.Letsou_Stiel
chemicals.viscosity.Przedziecki_Sridhar
chemicals.viscosity.Lucas
thermo.joback.Joback
References
----------
.. [1] Viswanath, Dabir S., and G. Natarajan. Databook On The Viscosity Of
Liquids. New York: Taylor & Francis, 1989
.. [2] Bell, Ian H., Jorrit Wronski, Sylvain Quoilin, and Vincent Lemort.
"Pure and Pseudo-Pure Fluid Thermophysical Property Evaluation and the
Open-Source Thermophysical Property Library CoolProp." Industrial &
Engineering Chemistry Research 53, no. 6 (February 12, 2014):
2498-2508. doi:10.1021/ie4033999. http://www.coolprop.org/
.. [3] Gesellschaft, V. D. I., ed. VDI Heat Atlas. 2nd edition.
Berlin; New York:: Springer, 2010.
.. [4] Green, Don, and Robert Perry. Perry's Chemical Engineers' Handbook,
Eighth Edition. McGraw-Hill Professional, 2007.
.. [5] Joback, K.G., and R.C. Reid. "Estimation of Pure-Component
Properties from Group-Contributions." Chemical Engineering
Communications 57, no. 1-6 (July 1, 1987): 233-43.
doi:10.1080/00986448708960487.
.. [6] Trachenko, K., and V. V. Brazhkin. "Minimal Quantum Viscosity from
Fundamental Physical Constants." Science Advances, April 2020.
https://doi.org/10.1126/sciadv.aba3747.
'''
name = 'liquid viscosity'
units = 'Pa*s'
@staticmethod
def interpolation_P(P):
'''log(P) interpolation transformation by default.
'''
return log(P)
@staticmethod
def interpolation_T(T):
'''Function to make the data-based interpolation as linear as possible.
This transforms the input `T` into the `1/T` domain.
'''
return 1./T
@staticmethod
def interpolation_property(P):
'''log(P) interpolation transformation by default.
'''
return log(P)
@staticmethod
def interpolation_property_inv(P):
'''exp(P) interpolation transformation by default; reverses
:obj:`interpolation_property_inv`.
'''
return exp(P)
tabular_extrapolation_permitted = True
"""Allow tabular extrapolation by default."""
property_min = 0.0
"""Mimimum valid value of liquid viscosity."""
property_max = 2E8
"""Maximum valid value of liquid viscosity. Generous limit, as
the value is that of bitumen in a Pitch drop experiment."""
ranked_methods = [REFPROP_FIT, COOLPROP, DIPPR_PERRY_8E, VDI_PPDS, DUTT_PRASAD, VISWANATH_NATARAJAN_3,
VISWANATH_NATARAJAN_2, VISWANATH_NATARAJAN_2E,
VDI_TABULAR, LETSOU_STIEL, JOBACK, PRZEDZIECKI_SRIDHAR]
"""Default rankings of the low-pressure methods."""
ranked_methods_P = [COOLPROP, LUCAS, NEGLECT_P]
"""Default rankings of the high-pressure methods."""
obj_references = pure_references = ('Psat', 'Vml')
obj_references_types = pure_reference_types = (VaporPressure, VolumeLiquid)
custom_args = ('MW', 'Tm', 'Tc', 'Pc', 'Vc', 'omega', 'Psat', 'Vml')
def __init__(self, CASRN='', MW=None, Tm=None, Tc=None, Pc=None, Vc=None,
omega=None, Psat=None, Vml=None, extrapolation='linear',
extrapolation_min=1e-5,
**kwargs):
self.CASRN = CASRN
self.MW = MW
self.Tm = Tm
self.Tc = Tc
self.Pc = Pc
self.Vc = Vc
self.omega = omega
self.Psat = Psat
self.Vml = Vml
if 'extrapolation_min' not in kwargs:
kwargs['extrapolation_min'] = extrapolation_min
super().__init__(extrapolation, **kwargs)
def load_all_methods(self, load_data=True):
r'''Method which picks out coefficients for the specified chemical
from the various dictionaries and DataFrames storing it. All data is
stored as attributes. This method also sets :obj:`Tmin`, :obj:`Tmax`,
:obj:`all_methods` and obj:`all_methods_P` as a set of methods for
which the data exists for.
Called on initialization only. See the source code for the variables at
which the coefficients are stored. The coefficients can safely be
altered once the class is initialized. This method can be called again
to reset the parameters.
'''
methods, methods_P = [], [NEGLECT_P]
self.T_limits = T_limits = {}
self.all_methods = set()
CASRN = self.CASRN
if load_data and CASRN:
CASRN_int = None if not CASRN else CAS_to_int(CASRN)
jb_df = miscdata.joback_predictions
if self.MW is not None and CASRN_int in jb_df.index:
mul0 = float(jb_df.at[CASRN_int, 'mul0'])
if not isnan(mul0):
methods.append(JOBACK)
self.joback_coeffs = [mul0, float(jb_df.at[CASRN_int, 'mul1'])]
Tmin_jb, Tmax_jb = float(jb_df.at[CASRN_int, 'Tm']), float(jb_df.at[CASRN_int, 'Tc'])*2.5
T_limits[JOBACK] = (Tmin_jb, Tmax_jb)
if has_CoolProp() and CASRN in coolprop_dict:
CP_f = coolprop_fluids[CASRN]
if CP_f.has_mu:
self.CP_f = CP_f
methods.append(COOLPROP)
methods_P.append(COOLPROP)
T_limits[COOLPROP] = (self.CP_f.Tmin, self.CP_f.Tc)
if CASRN in miscdata.VDI_saturation_dict:
Ts, props = lookup_VDI_tabular_data(CASRN, 'Mu (l)')
self.add_tabular_data(Ts, props, VDI_TABULAR, check_properties=False)
del self._method
if CASRN in viscosity.mu_data_Dutt_Prasad.index:
methods.append(DUTT_PRASAD)
A, B, C, self.DUTT_PRASAD_Tmin, self.DUTT_PRASAD_Tmax = viscosity.mu_values_Dutt_Prasad[viscosity.mu_data_Dutt_Prasad.index.get_loc(CASRN)].tolist()
self.DUTT_PRASAD_coeffs = [A - 3.0, B, C]
T_limits[DUTT_PRASAD] = (self.DUTT_PRASAD_Tmin, self.DUTT_PRASAD_Tmax)
if CASRN in viscosity.mu_data_VN3.index:
methods.append(VISWANATH_NATARAJAN_3)
A, B, C, self.VISWANATH_NATARAJAN_3_Tmin, self.VISWANATH_NATARAJAN_3_Tmax = viscosity.mu_values_VN3[viscosity.mu_data_VN3.index.get_loc(CASRN)].tolist()
self.VISWANATH_NATARAJAN_3_coeffs = [A - 3.0, B, C]
T_limits[VISWANATH_NATARAJAN_3] = (self.VISWANATH_NATARAJAN_3_Tmin, self.VISWANATH_NATARAJAN_3_Tmax)
if CASRN in viscosity.mu_data_VN2.index:
methods.append(VISWANATH_NATARAJAN_2)
A, B, self.VISWANATH_NATARAJAN_2_Tmin, self.VISWANATH_NATARAJAN_2_Tmax = viscosity.mu_values_VN2[viscosity.mu_data_VN2.index.get_loc(CASRN)].tolist()
self.VISWANATH_NATARAJAN_2_coeffs = [A - 4.605170185988092, B] # log(100) = 4.605170185988092
T_limits[VISWANATH_NATARAJAN_2] = (self.VISWANATH_NATARAJAN_2_Tmin, self.VISWANATH_NATARAJAN_2_Tmax)
if CASRN in viscosity.mu_data_VN2E.index:
methods.append(VISWANATH_NATARAJAN_2E)
C, D, self.VISWANATH_NATARAJAN_2E_Tmin, self.VISWANATH_NATARAJAN_2E_Tmax = viscosity.mu_values_VN2E[viscosity.mu_data_VN2E.index.get_loc(CASRN)].tolist()
self.VISWANATH_NATARAJAN_2E_coeffs = [C, D]
T_limits[VISWANATH_NATARAJAN_2E] = (self.VISWANATH_NATARAJAN_2E_Tmin, self.VISWANATH_NATARAJAN_2E_Tmax)
if CASRN in viscosity.mu_data_Perrys_8E_2_313.index:
methods.append(DIPPR_PERRY_8E)
C1, C2, C3, C4, C5, self.Perrys2_313_Tmin, self.Perrys2_313_Tmax = viscosity.mu_values_Perrys_8E_2_313[viscosity.mu_data_Perrys_8E_2_313.index.get_loc(CASRN)].tolist()
self.Perrys2_313_coeffs = [C1, C2, C3, C4, C5]
T_limits[DIPPR_PERRY_8E] = (self.Perrys2_313_Tmin, self.Perrys2_313_Tmax)
if CASRN in viscosity.mu_data_VDI_PPDS_7.index:
methods.append(VDI_PPDS)
# No temperature limits - ideally could use critical point
self.VDI_PPDS_coeffs = VDI_PPDS_coeffs = viscosity.mu_values_PPDS_7[viscosity.mu_data_VDI_PPDS_7.index.get_loc(CASRN)].tolist()
low = low_orig = min(self.VDI_PPDS_coeffs[2], self.VDI_PPDS_coeffs[3])# + 5.0
high = high_orig = max(self.VDI_PPDS_coeffs[2], self.VDI_PPDS_coeffs[3])# - 5.0
if low > 0.0:
dmu_low_under, mu_low_under = dPPDS9_dT(low*0.9995, *VDI_PPDS_coeffs)
dmu_low_above, mu_low_above = dPPDS9_dT(low*1.0005, *VDI_PPDS_coeffs)
if high > 0.0:
dmu_high_under, mu_high_under = dPPDS9_dT(high*0.9995, *VDI_PPDS_coeffs)
dmu_high_above, mu_high_above = dPPDS9_dT(high*1.0005, *VDI_PPDS_coeffs)
if self.Tm is not None:
dmu_Tm, mu_Tm = dPPDS9_dT(self.Tm, *VDI_PPDS_coeffs)
if self.Tc is not None:
dmu_Tc_under, mu_Tc_under = dPPDS9_dT(self.Tc, *VDI_PPDS_coeffs)
if high > 0.0 and low < 0.0 or isinf(dmu_low_under) or isinf(dmu_low_above):
# high + a few K as lower limit
low = 0.1*high
high = high-1.0
else:
low, high = low + 5.0, high + 5.0
if self.Tm is not None:
low = self.Tm
if self.Tc is not None:
if dmu_Tc_under < 0.0:
high = self.Tc
if self.Tm is not None and self.Tc is not None and low_orig < 0 and self.Tm < high_orig < self.Tc and dmu_Tc_under < 0.0:
low = high_orig + 1.0
if high == high_orig:
high -= 1.0
dmu_low, mu_low = dPPDS9_dT(low, *VDI_PPDS_coeffs)
dmu_high, mu_high = dPPDS9_dT(high, *VDI_PPDS_coeffs)
if dmu_low*dmu_high < 0.0:
def to_solve(T):
return dPPDS9_dT(T, *VDI_PPDS_coeffs)[0]
T_switch = brenth(to_solve, low, high)
if dmu_high > 0.0:
high = T_switch
else:
low = T_switch
T_limits[VDI_PPDS] = (low, high)
if all((self.MW, self.Tc, self.Pc, self.omega)):
methods.append(LETSOU_STIEL)
T_limits[LETSOU_STIEL] = (self.Tc/4, self.Tc)
if all((self.MW, self.Tm, self.Tc, self.Pc, self.Vc, self.omega, self.Vml)):
methods.append(PRZEDZIECKI_SRIDHAR)
T_limits[PRZEDZIECKI_SRIDHAR] = (self.Tm, self.Tc)
if all([self.Tc, self.Pc, self.omega]):
methods_P.append(LUCAS)
self.all_methods.update(methods)
self.all_methods_P = set(methods_P)
@staticmethod
def _method_indexes():
'''Returns a dictionary of method: index for all methods
that use data files to retrieve constants. The use of this function
ensures the data files are not loaded until they are needed.
'''
return {COOLPROP : [CAS for CAS in coolprop_dict if (coolprop_fluids[CAS].has_mu and CAS not in CoolProp_failing_PT_flashes)],
VDI_TABULAR: list(miscdata.VDI_saturation_dict.keys()),
DUTT_PRASAD: viscosity.mu_data_Dutt_Prasad.index,
VISWANATH_NATARAJAN_3: viscosity.mu_data_VN3.index,
VISWANATH_NATARAJAN_2: viscosity.mu_data_VN2.index,
VISWANATH_NATARAJAN_2E: viscosity.mu_data_VN2E.index,
DIPPR_PERRY_8E: viscosity.mu_data_Perrys_8E_2_313.index,
VDI_PPDS: viscosity.mu_data_VDI_PPDS_7.index,
}
[docs] def calculate(self, T, method):
r'''Method to calculate low-pressure liquid viscosity at tempearture
`T` with a given method.
This method has no exception handling; see :obj:`T_dependent_property <thermo.utils.TDependentProperty.T_dependent_property>`
for that.
Parameters
----------
T : float
Temperature at which to calculate viscosity, [K]
method : str
Name of the method to use
Returns
-------
mu : float
Viscosity of the liquid at T and a low pressure, [Pa*s]
'''
if method == DUTT_PRASAD:
A, B, C = self.DUTT_PRASAD_coeffs
mu = Viswanath_Natarajan_3(T, A, B, C, )
elif method == VISWANATH_NATARAJAN_3:
A, B, C = self.VISWANATH_NATARAJAN_3_coeffs
mu = Viswanath_Natarajan_3(T, A, B, C)
elif method == VISWANATH_NATARAJAN_2:
A, B = self.VISWANATH_NATARAJAN_2_coeffs
mu = Viswanath_Natarajan_2(T, self.VISWANATH_NATARAJAN_2_coeffs[0], self.VISWANATH_NATARAJAN_2_coeffs[1])
elif method == VISWANATH_NATARAJAN_2E:
C, D = self.VISWANATH_NATARAJAN_2E_coeffs
mu = Viswanath_Natarajan_2_exponential(T, C, D)
elif method == DIPPR_PERRY_8E:
mu = EQ101(T, *self.Perrys2_313_coeffs)
elif method == COOLPROP:
mu = CoolProp_T_dependent_property(T, self.CASRN, 'V', 'l')
elif method == JOBACK:
A, B = self.joback_coeffs
mu = self.MW*exp(A/T + B)
elif method == LETSOU_STIEL:
mu = Letsou_Stiel(T, self.MW, self.Tc, self.Pc, self.omega)
elif method == PRZEDZIECKI_SRIDHAR:
if type(self.Vml) is float:
Vml = self.Vml
elif type(self.Vml) is VolumeLiquid:
Vml = self.Vml.T_dependent_property(T)
else:
Vml = self.Vml(T)
mu = Przedziecki_Sridhar(T, self.Tm, self.Tc, self.Pc, self.Vc, Vml, self.omega, self.MW)
elif method == VDI_PPDS:
return PPDS9(T, *self.VDI_PPDS_coeffs)
else:
return self._base_calculate(T, method)
return mu
[docs] def test_method_validity(self, T, method):
r'''Method to check the validity of a method. Follows the given
ranges for all coefficient-based methods. For CSP methods, the models
are considered valid from 0 K to the critical point. For tabular data,
extrapolation outside of the range is used if
:obj:`tabular_extrapolation_permitted` is set; if it is, the
extrapolation is considered valid for all temperatures.
It is not guaranteed that a method will work or give an accurate
prediction simply because this method considers the method valid.
Parameters
----------
T : float
Temperature at which to test the method, [K]
method : str
Name of the method to test
Returns
-------
validity : bool
Whether or not a method is valid
'''
try:
low, high = self.T_limits[method]
return low <= T <= high
except:
pass
if method == DUTT_PRASAD:
if T < self.DUTT_PRASAD_Tmin or T > self.DUTT_PRASAD_Tmax:
return False
elif method == VISWANATH_NATARAJAN_3:
if T < self.VISWANATH_NATARAJAN_3_Tmin or T > self.VISWANATH_NATARAJAN_3_Tmax:
return False
elif method == VISWANATH_NATARAJAN_2:
if T < self.VISWANATH_NATARAJAN_2_Tmin or T > self.VISWANATH_NATARAJAN_2_Tmax:
return False
elif method == VISWANATH_NATARAJAN_2E:
if T < self.VISWANATH_NATARAJAN_2E_Tmin or T > self.VISWANATH_NATARAJAN_2E_Tmax:
return False
elif method == DIPPR_PERRY_8E:
if T < self.Perrys2_313_Tmin or T > self.Perrys2_313_Tmax:
return False
elif method == COOLPROP:
if T < self.CP_f.Tmin or T < self.CP_f.Tt or T > self.CP_f.Tc:
return False
elif method in (LETSOU_STIEL, PRZEDZIECKI_SRIDHAR):
if T > self.Tc:
return False
# No lower limit
elif method == VDI_PPDS:
# If the derivative is positive, return invalid.
# This is very important as no maximum temperatures are specified.
if self.Tc and T > self.Tc:
return False
A, B, C, D, E = self.VDI_PPDS_coeffs
term = (C - T)/(T - D)
# Derived with sympy
return True
try:
if term > 0:
der = E*((-C + T)/(D - T))**(1/3.)*(A + 4*B*(-C + T)/(D - T))*(C - D)*exp(((-C + T)/(D - T))**(1/3.)*(A + B*(-C + T)/(D - T)))/(3*(C - T)*(D - T))
else:
der = E*((C - T)/(D - T))**(1/3.)*(-A*(C - D)*(D - T)**6 + B*(C - D)*(C - T)*(D - T)**5 + 3*B*(C - T)**2*(D - T)**5 - 3*B*(C - T)*(D - T)**6)*exp(-((C - T)/(D - T))**(1/3.)*(A*(D - T) - B*(C - T))/(D - T))/(3*(C - T)*(D - T)**7)
return der < 0
except:
return False
else:
return super().test_method_validity(T, method)
return True
[docs] def calculate_P(self, T, P, method):
r'''Method to calculate pressure-dependent liquid viscosity at
temperature `T` and pressure `P` with a given method.
This method has no exception handling; see :obj:`TP_dependent_property <thermo.utils.TPDependentProperty.TP_dependent_property>`
for that.
Parameters
----------
T : float
Temperature at which to calculate viscosity, [K]
P : float
Pressure at which to calculate viscosity, [K]
method : str
Name of the method to use
Returns
-------
mu : float
Viscosity of the liquid at T and P, [Pa*s]
'''
if method == LUCAS:
mu = self.T_dependent_property(T)
Psat = self.Psat(T) if hasattr(self.Psat, '__call__') else self.Psat
mu = Lucas(T, P, self.Tc, self.Pc, self.omega, Psat, mu)
elif method == COOLPROP:
mu = PropsSI('V', 'T', T, 'P', P, self.CASRN)
else:
return self._base_calculate_P(T, P, method)
return mu
[docs] def test_method_validity_P(self, T, P, method):
r'''Method to check the validity of a high-pressure method. For
**COOLPROP**, the fluid must be both a liquid and under the maximum
pressure of the fluid's EOS. **LUCAS** doesn't work on some occasions,
due to something related to Tr and negative powers - but is otherwise
considered correct for all circumstances.
For tabular data, extrapolation outside of the range is used if
:obj:`tabular_extrapolation_permitted` is set; if it is, the
extrapolation is considered valid for all temperatures and pressures.
Parameters
----------
T : float
Temperature at which to test the method, [K]
P : float
Pressure at which to test the method, [Pa]
method : str
Name of the method to test
Returns
-------
validity : bool
Whether or not a method is valid
'''
if method == LUCAS:
validity = True
elif method == COOLPROP:
validity = PhaseSI('T', T, 'P', P, self.CASRN) in ['liquid', 'supercritical_liquid']
else:
validity = super().test_method_validity_P(T, P, method)
return validity
GHARAGHEIZI = 'GHARAGHEIZI'
YOON_THODOS = 'YOON_THODOS'
STIEL_THODOS = 'STIEL_THODOS'
LUCAS_GAS = 'LUCAS_GAS'
viscosity_gas_methods = [REFPROP_FIT, COOLPROP, DIPPR_PERRY_8E, VDI_PPDS, VDI_TABULAR, GHARAGHEIZI, YOON_THODOS,
STIEL_THODOS, LUCAS_GAS]
"""Holds all low-pressure methods available for the ViscosityGas
class, for use in iterating over them."""
viscosity_gas_methods_P = [NEGLECT_P, COOLPROP]
"""Holds all high-pressure methods available for the ViscosityGas
class, for use in iterating over them."""
[docs]class ViscosityGas(TPDependentProperty):
r'''Class for dealing with gas viscosity as a function of
temperature and pressure.
For gases at atmospheric pressure, there are 4 corresponding-states
estimators, two sources of coefficient-based models, one source of tabular
information, and the external library CoolProp.
For gases under the fluid's boiling point (at sub-atmospheric pressures),
and high-pressure gases above the boiling point, there are zero
corresponding-states estimators, and the external library CoolProp.
Parameters
----------
CASRN : str, optional
The CAS number of the chemical
MW : float, optional
Molecular weight, [g/mol]
Tc : float, optional
Critical temperature, [K]
Pc : float, optional
Critical pressure, [Pa]
Zc : float, optional
Critical compressibility, [-]
dipole : float, optional
Dipole moment of the fluid, [debye]
Vmg : float, optional
Molar volume of the fluid at a pressure and temperature, [m^3/mol]
load_data : bool, optional
If False, do not load property coefficients from data sources in files
[-]
extrapolation : str or None
None to not extrapolate; see
:obj:`TDependentProperty <thermo.utils.TDependentProperty>`
for a full list of all options, [-]
method : str or None, optional
If specified, use this method by default and do not use the ranked
sorting; an exception is raised if this is not a valid method for the
provided inputs, [-]
Notes
-----
A string holding each method's name is assigned to the following variables
in this module, intended as the most convenient way to refer to a method.
To iterate over all methods, use the lists stored in
:obj:`viscosity_gas_methods` and
:obj:`viscosity_gas_methods_P` for low and high pressure
methods respectively.
Low pressure methods:
**GHARAGHEIZI**:
CSP method, described in :obj:`chemicals.viscosity.Gharagheizi_gas_viscosity`.
**YOON_THODOS**:
CSP method, described in :obj:`chemicals.viscosity.Yoon_Thodos`.
**STIEL_THODOS**:
CSP method, described in :obj:`chemicals.viscosity.Stiel_Thodos`.
**LUCAS_GAS**:
CSP method, described in :obj:`chemicals.viscosity.Lucas_gas`.
**DIPPR_PERRY_8E**:
A collection of 345 coefficient sets from the DIPPR database published
openly in [3]_. Provides temperature limits for all its fluids.
:obj:`chemicals.dippr.EQ102` is used for its fluids.
**VDI_PPDS**:
Coefficients for a equation form developed by the PPDS, published
openly in [2]_. Provides no temperature limits, but provides reasonable
values at fairly high and very low temperatures.
**COOLPROP**:
CoolProp external library; with select fluids from its library.
Range is limited to that of the equations of state it uses, as
described in [1]_. Very slow.
**VDI_TABULAR**:
Tabular data in [2]_ along the saturation curve; interpolation is as
set by the user or the default.
**REFPROP_FIT**:
A series of higher-order polynomial fits to the calculated results from
the equations implemented in REFPROP.
High pressure methods:
**COOLPROP**:
CoolProp external library; with select fluids from its library.
Range is limited to that of the equations of state it uses, as
described in [1]_. Very slow, but unparalled in accuracy for pressure
dependence.
A minimum viscosity value of 1e-5 Pa*s is set according to [4]_.
This is also just above the lowest experimental values of viscosity of
helium, 9.4e-6 Pa*s.
See Also
--------
chemicals.viscosity.Gharagheizi_gas_viscosity
chemicals.viscosity.Yoon_Thodos
chemicals.viscosity.Stiel_Thodos
chemicals.viscosity.Lucas_gas
References
----------
.. [1] Bell, Ian H., Jorrit Wronski, Sylvain Quoilin, and Vincent Lemort.
"Pure and Pseudo-Pure Fluid Thermophysical Property Evaluation and the
Open-Source Thermophysical Property Library CoolProp." Industrial &
Engineering Chemistry Research 53, no. 6 (February 12, 2014):
2498-2508. doi:10.1021/ie4033999. http://www.coolprop.org/
.. [2] Gesellschaft, V. D. I., ed. VDI Heat Atlas. 2nd edition.
Berlin; New York:: Springer, 2010.
.. [3] Green, Don, and Robert Perry. Perry's Chemical Engineers' Handbook,
Eighth Edition. McGraw-Hill Professional, 2007.
.. [4] Trachenko, K., and V. V. Brazhkin. "Minimal Quantum Viscosity from
Fundamental Physical Constants." Science Advances, April 2020.
https://doi.org/10.1126/sciadv.aba3747.
'''
name = 'Gas viscosity'
units = 'Pa*s'
interpolation_T = None
"""No interpolation transformation by default."""
interpolation_P = None
"""No interpolation transformation by default."""
interpolation_property = None
"""No interpolation transformation by default."""
interpolation_property_inv = None
"""No interpolation transformation by default."""
tabular_extrapolation_permitted = True
"""Allow tabular extrapolation by default."""
property_min = 0.0
"""Mimimum valid value of gas viscosity; limiting condition at low pressure
is 0."""
property_max = 1E-3
"""Maximum valid value of gas viscosity. Might be too high, or too low."""
ranked_methods = [REFPROP_FIT, COOLPROP, DIPPR_PERRY_8E, VDI_PPDS, VDI_TABULAR, GHARAGHEIZI, YOON_THODOS,
STIEL_THODOS, LUCAS_GAS]
"""Default rankings of the low-pressure methods."""
ranked_methods_P = [NEGLECT_P, COOLPROP]
"""Default rankings of the high-pressure methods."""
obj_references = pure_references = ('Vmg',)
obj_references_types = pure_reference_types = (VolumeGas,)
custom_args = ('MW', 'Tc', 'Pc', 'Zc', 'dipole', 'Vmg')
def __init__(self, CASRN='', MW=None, Tc=None, Pc=None, Zc=None,
dipole=None, Vmg=None, extrapolation='linear', extrapolation_min=1e-5,
**kwargs):
self.CASRN = CASRN
self.MW = MW
self.Tc = Tc
self.Pc = Pc
self.Zc = Zc
self.dipole = dipole
self.Vmg = Vmg
if 'extrapolation_min' not in kwargs:
kwargs['extrapolation_min'] = extrapolation_min
super().__init__(extrapolation, **kwargs)
def load_all_methods(self, load_data=True):
r'''Method which picks out coefficients for the specified chemical
from the various dictionaries and DataFrames storing it. All data is
stored as attributes. This method also sets :obj:`Tmin`, :obj:`Tmax`,
:obj:`all_methods` and obj:`all_methods_P` as a set of methods for
which the data exists for.
Called on initialization only. See the source code for the variables at
which the coefficients are stored. The coefficients can safely be
altered once the class is initialized. This method can be called again
to reset the parameters.
'''
methods, methods_P = [], [NEGLECT_P]
self.T_limits = T_limits = {}
self.all_methods = set()
CASRN = self.CASRN
if load_data and CASRN:
if CASRN in miscdata.VDI_saturation_dict:
Ts, props = lookup_VDI_tabular_data(CASRN, 'Mu (g)')
self.add_tabular_data(Ts, props, VDI_TABULAR, check_properties=False)
del self._method
if has_CoolProp() and CASRN in coolprop_dict:
CP_f = coolprop_fluids[CASRN]
if CP_f.has_mu:
self.CP_f = CP_f
methods.append(COOLPROP)
methods_P.append(COOLPROP)
# T_limits[COOLPROP] = (self.CP_f.Tmin, self.CP_f.Tmax)
T_limits[COOLPROP] = (self.CP_f.Tmin, self.CP_f.Tmax*.9999)
if CASRN in viscosity.mu_data_Perrys_8E_2_312.index:
methods.append(DIPPR_PERRY_8E)
C1, C2, C3, C4, self.Perrys2_312_Tmin, self.Perrys2_312_Tmax = viscosity.mu_values_Perrys_8E_2_312[viscosity.mu_data_Perrys_8E_2_312.index.get_loc(CASRN)].tolist()
self.Perrys2_312_coeffs = [C1, C2, C3, C4]
T_limits[DIPPR_PERRY_8E] = (self.Perrys2_312_Tmin, self.Perrys2_312_Tmax)
if CASRN in viscosity.mu_data_VDI_PPDS_8.index:
methods.append(VDI_PPDS)
self.VDI_PPDS_coeffs = viscosity.mu_values_PPDS_8[viscosity.mu_data_VDI_PPDS_8.index.get_loc(CASRN)].tolist()
self.VDI_PPDS_coeffs.reverse() # in format for horner's scheme
T_limits[VDI_PPDS] = (1e-3, 10000)
if all([self.Tc, self.Pc, self.MW]):
methods.append(GHARAGHEIZI)
methods.append(YOON_THODOS)
methods.append(STIEL_THODOS)
T_limits[YOON_THODOS] = T_limits[STIEL_THODOS] = T_limits[GHARAGHEIZI] = (1e-3, 5E3)
# GHARAGHEIZI turns nonsesical at ~15 K, YOON_THODOS fine to 0 K,
# same as STIEL_THODOS
if all([self.Tc, self.Pc, self.Zc, self.MW]):
methods.append(LUCAS_GAS)
T_limits[LUCAS_GAS] = (1e-3, 1E3)
self.all_methods.update(methods)
self.all_methods_P = set(methods_P)
@staticmethod
def _method_indexes():
'''Returns a dictionary of method: index for all methods
that use data files to retrieve constants. The use of this function
ensures the data files are not loaded until they are needed.
'''
return {COOLPROP : [CAS for CAS in coolprop_dict if (coolprop_fluids[CAS].has_mu and CAS not in CoolProp_failing_PT_flashes)],
VDI_TABULAR: list(miscdata.VDI_saturation_dict.keys()),
DIPPR_PERRY_8E: viscosity.mu_data_Perrys_8E_2_312.index,
VDI_PPDS: viscosity.mu_data_VDI_PPDS_8.index,
}
[docs] def calculate(self, T, method):
r'''Method to calculate low-pressure gas viscosity at
tempearture `T` with a given method.
This method has no exception handling; see :obj:`T_dependent_property <thermo.utils.TDependentProperty.T_dependent_property>`
for that.
Parameters
----------
T : float
Temperature of the gas, [K]
method : str
Name of the method to use
Returns
-------
mu : float
Viscosity of the gas at T and a low pressure, [Pa*s]
'''
if method == GHARAGHEIZI:
mu = viscosity_gas_Gharagheizi(T, self.Tc, self.Pc, self.MW)
elif method == COOLPROP:
mu = CoolProp_T_dependent_property(T, self.CASRN, 'V', 'g')
elif method == DIPPR_PERRY_8E:
mu = EQ102(T, *self.Perrys2_312_coeffs)
elif method == VDI_PPDS:
mu = horner(self.VDI_PPDS_coeffs, T)
elif method == YOON_THODOS:
mu = Yoon_Thodos(T, self.Tc, self.Pc, self.MW)
elif method == STIEL_THODOS:
mu = Stiel_Thodos(T, self.Tc, self.Pc, self.MW)
elif method == LUCAS_GAS:
mu = Lucas_gas(T, self.Tc, self.Pc, self.Zc, self.MW, self.dipole, CASRN=self.CASRN)
else:
return self._base_calculate(T, method)
return mu
[docs] def test_method_validity(self, T, method):
r'''Method to check the validity of a temperature-dependent
low-pressure method. For CSP most methods, the all methods are
considered valid from 0 K up to 5000 K. For method **GHARAGHEIZI**,
the method is considered valud from 20 K to 2000 K.
For tabular data, extrapolation outside of the range is used if
:obj:`tabular_extrapolation_permitted` is set; if it is, the extrapolation
is considered valid for all temperatures.
It is not guaranteed that a method will work or give an accurate
prediction simply because this method considers the method valid.
Parameters
----------
T : float
Temperature at which to test the method, [K]
method : str
Name of the method to test
Returns
-------
validity : bool
Whether or not a method is valid
'''
validity = True
if method in (YOON_THODOS, STIEL_THODOS, LUCAS_GAS):
if T < 0 or T > 5000:
# Arbitrary limit
return False
elif method == DIPPR_PERRY_8E:
if T < self.Perrys2_312_Tmin or T > self.Perrys2_312_Tmax:
return False
elif method == GHARAGHEIZI:
if T < 20 or T > 2E3:
validity = False
# Doesn't do so well as the other methods
elif method == COOLPROP:
if T < self.CP_f.Tmin or T > self.CP_f.Tmax:
return False
elif method == VDI_PPDS:
pass # Polynomial always works
else:
return super().test_method_validity(T, method)
return validity
[docs] def calculate_P(self, T, P, method):
r'''Method to calculate pressure-dependent gas viscosity
at temperature `T` and pressure `P` with a given method.
This method has no exception handling; see :obj:`TP_dependent_property <thermo.utils.TPDependentProperty.TP_dependent_property>`
for that.
Parameters
----------
T : float
Temperature at which to calculate gas viscosity, [K]
P : float
Pressure at which to calculate gas viscosity, [K]
method : str
Name of the method to use
Returns
-------
mu : float
Viscosity of the gas at T and P, [Pa*]
'''
if method == COOLPROP:
mu = PropsSI('V', 'T', T, 'P', P, self.CASRN)
else:
return self._base_calculate_P(T, P, method)
return mu
[docs] def test_method_validity_P(self, T, P, method):
r'''Method to check the validity of a high-pressure method. For
**COOLPROP**, the fluid must be both a gas and under the maximum
pressure of the fluid's EOS. No other methods are implemented.
For tabular data, extrapolation outside of the range is used if
:obj:`tabular_extrapolation_permitted` is set; if it is, the
extrapolation is considered valid for all temperatures and pressures.
It is not guaranteed that a method will work or give an accurate
prediction simply because this method considers the method valid.
Parameters
----------
T : float
Temperature at which to test the method, [K]
P : float
Pressure at which to test the method, [Pa]
method : str
Name of the method to test
Returns
-------
validity : bool
Whether or not a method is valid
'''
validity = True
if method == COOLPROP:
validity = PhaseSI('T', T, 'P', P, self.CASRN) in ['gas', 'supercritical_gas', 'supercritical', 'supercritical_liquid']
else:
validity = super().test_method_validity_P(T, P, method)
return validity
LALIBERTE_MU = 'Laliberte'
viscosity_liquid_mixture_methods = [LALIBERTE_MU, MIXING_LOG_MOLAR, MIXING_LOG_MASS, LINEAR]
"""Holds all mixing rules available for the :obj:`ViscosityLiquidMixture`
class, for use in iterating over them."""
[docs]class ViscosityLiquidMixture(MixtureProperty):
'''Class for dealing with the viscosity of a liquid mixture as a
function of temperature, pressure, and composition.
Consists of one electrolyte-specific method, and logarithmic rules based
on either mole fractions of mass fractions.
Prefered method is :obj:`mixing_logarithmic <chemicals.utils.mixing_logarithmic>` with mole
fractions, or **Laliberte** if the mixture is aqueous and has electrolytes.
Parameters
----------
CASs : list[str], optional
The CAS numbers of all species in the mixture, [-]
ViscosityLiquids : list[ViscosityLiquid], optional
ViscosityLiquid objects created for all species in the mixture, [-]
MWs : list[float], optional
Molecular weights of all species in the mixture, [g/mol]
correct_pressure_pure : bool, optional
Whether to try to use the better pressure-corrected pure component
models or to use only the T-only dependent pure species models, [-]
Notes
-----
To iterate over all methods, use the list stored in
:obj:`viscosity_liquid_mixture_methods`.
**LALIBERTE_MU**:
Electrolyte model equation with coefficients; see
:obj:`thermo.electrochem.Laliberte_viscosity` for more details.
**MIXING_LOG_MOLAR**:
Logarithmic mole fraction mixing rule described in
:obj:`chemicals.utils.mixing_logarithmic`.
**MIXING_LOG_MASS**:
Logarithmic mole fraction mixing rule described in
:obj:`chemicals.utils.mixing_logarithmic`.
**LINEAR**:
Linear mole fraction mixing rule described in
:obj:`mixing_simple <chemicals.utils.mixing_simple>`.
See Also
--------
:obj:`thermo.electrochem.Laliberte_viscosity`
References
----------
.. [1] Poling, Bruce E. The Properties of Gases and Liquids. 5th edition.
New York: McGraw-Hill Professional, 2000.
'''
name = 'liquid viscosity'
units = 'Pa*s'
property_min = 0
"""Mimimum valid value of liquid viscosity."""
property_max = 2E8
"""Maximum valid value of liquid viscosity. Generous limit, as
the value is that of bitumen in a Pitch drop experiment."""
ranked_methods = [LALIBERTE_MU, MIXING_LOG_MOLAR, MIXING_LOG_MASS, LINEAR]
pure_references = ('ViscosityLiquids',)
pure_reference_types = (ViscosityLiquid, )
pure_constants = ('MWs', )
custom_args = pure_constants
def __init__(self, CASs=[], ViscosityLiquids=[], MWs=[], **kwargs):
self.CASs = CASs
self.ViscosityLiquids = ViscosityLiquids
self.MWs = MWs
super().__init__(**kwargs)
def load_all_methods(self):
r'''Method to initialize the object by precomputing any values which
may be used repeatedly and by retrieving mixture-specific variables.
All data are stored as attributes. This method also sets :obj:`Tmin`,
:obj:`Tmax`, and :obj:`all_methods` as a set of methods which should
work to calculate the property.
Called on initialization only. See the source code for the variables at
which the coefficients are stored. The coefficients can safely be
altered once the class is initialized. This method can be called again
to reset the parameters.
'''
methods = [MIXING_LOG_MOLAR, MIXING_LOG_MASS, LINEAR]
if len(self.CASs) > 1 and '7732-18-5' in self.CASs:
wCASs = [i for i in self.CASs if i != '7732-18-5']
Laliberte_data = electrochem.Laliberte_data
laliberte_incomplete = False
v1s, v2s, v3s, v4s, v5s, v6s = [], [], [], [], [], []
for CAS in wCASs:
if CAS in Laliberte_data.index:
dat = Laliberte_data.loc[CAS].values
if isnan(dat[12]):
laliberte_incomplete = True
break
v1s.append(float(dat[12]))
v2s.append(float(dat[13]))
v3s.append(float(dat[14]))
v4s.append(float(dat[15]))
v5s.append(float(dat[16]))
v6s.append(float(dat[17]))
else:
laliberte_incomplete = True
break
if not laliberte_incomplete:
methods.append(LALIBERTE_MU)
self.wCASs = wCASs
self.index_w = self.CASs.index('7732-18-5')
self.Laliberte_v1s = v1s
self.Laliberte_v2s = v2s
self.Laliberte_v3s = v3s
self.Laliberte_v4s = v4s
self.Laliberte_v5s = v5s
self.Laliberte_v6s = v6s
self.all_methods = all_methods = set(methods)
Tmins = [i.Tmin for i in self.ViscosityLiquids if i.Tmin]
Tmaxs = [i.Tmax for i in self.ViscosityLiquids if i.Tmax]
if Tmins:
self.Tmin = max(Tmins)
if Tmaxs:
self.Tmax = max(Tmaxs)
[docs] def calculate(self, T, P, zs, ws, method):
r'''Method to calculate viscosity of a liquid mixture at
temperature `T`, pressure `P`, mole fractions `zs` and weight fractions
`ws` with a given method.
This method has no exception handling; see :obj:`mixture_property <thermo.utils.MixtureProperty.mixture_property>`
for that.
Parameters
----------
T : float
Temperature at which to calculate the property, [K]
P : float
Pressure at which to calculate the property, [Pa]
zs : list[float]
Mole fractions of all species in the mixture, [-]
ws : list[float]
Weight fractions of all species in the mixture, [-]
method : str
Name of the method to use
Returns
-------
mu : float
Viscosity of the liquid mixture, [Pa*s]
'''
if method == LALIBERTE_MU:
ws = list(ws)
ws.pop(self.index_w)
return Laliberte_viscosity(T, ws, self.wCASs)
return super().calculate(T, P, zs, ws, method)
[docs] def test_method_validity(self, T, P, zs, ws, method):
r'''Method to test the validity of a specified method for the given
conditions. If **Laliberte** is applicable, all other methods are
returned as inapplicable. Otherwise, there are no checks or strict
ranges of validity.
Parameters
----------
T : float
Temperature at which to check method validity, [K]
P : float
Pressure at which to check method validity, [Pa]
zs : list[float]
Mole fractions of all species in the mixture, [-]
ws : list[float]
Weight fractions of all species in the mixture, [-]
method : str
Method name to use
Returns
-------
validity : bool
Whether or not a specifid method is valid
'''
if LALIBERTE_MU in self.all_methods:
# If everything is an electrolyte, accept only it as a method
if method in self.all_methods:
return method == LALIBERTE_MU
if method in self.all_methods:
return True
return super().test_method_validity(T, P, zs, ws, method)
BROKAW = 'BROKAW'
HERNING_ZIPPERER = 'HERNING_ZIPPERER'
WILKE = 'WILKE'
viscosity_gas_mixture_methods = [BROKAW, HERNING_ZIPPERER, WILKE, LINEAR]
"""Holds all mixing rules available for the :obj:`ViscosityGasMixture`
class, for use in iterating over them."""
[docs]class ViscosityGasMixture(MixtureProperty):
'''Class for dealing with the viscosity of a gas mixture as a
function of temperature, pressure, and composition.
Consists of three gas viscosity specific mixing rules and a mole-weighted
simple mixing rule.
Prefered method is :obj:`Brokaw <chemicals.viscosity.Brokaw>`.
Parameters
----------
MWs : list[float], optional
Molecular weights of all species in the mixture, [g/mol]
molecular_diameters : list[float], optional
Lennard-Jones molecular diameters, [angstrom]
Stockmayers : list[float], optional
Lennard-Jones depth of potential-energy minimum over k
or epsilon_k, [K]
CASs : list[str], optional
The CAS numbers of all species in the mixture, [-]
ViscosityGases : list[ViscosityGas], optional
ViscosityGas objects created for all species in the mixture, [-]
correct_pressure_pure : bool, optional
Whether to try to use the better pressure-corrected pure component
models or to use only the T-only dependent pure species models, [-]
Notes
-----
To iterate over all methods, use the list stored in
:obj:`viscosity_liquid_mixture_methods`.
**BROKAW**:
Mixing rule described in :obj:`Brokaw <chemicals.viscosity.Brokaw>`.
**HERNING_ZIPPERER**:
Mixing rule described in :obj:`Herning_Zipperer <chemicals.viscosity.Herning_Zipperer>`.
**WILKE**:
Mixing rule described in :obj:`Wilke <chemicals.viscosity.Wilke>`.
**LINEAR**:
Mixing rule described in :obj:`mixing_simple <chemicals.utils.mixing_simple>`.
See Also
--------
chemicals.viscosity.Brokaw
chemicals.viscosity.Herning_Zipperer
chemicals.viscosity.Wilke
References
----------
.. [1] Poling, Bruce E. The Properties of Gases and Liquids. 5th edition.
New York: McGraw-Hill Professional, 2000.
'''
name = 'gas viscosity'
units = 'Pa*s'
property_min = 0
"""Mimimum valid value of gas viscosity; limiting condition at low pressure
is 0."""
property_max = 1E-3
"""Maximum valid value of gas viscosity. Might be too high, or too low."""
ranked_methods = [BROKAW, HERNING_ZIPPERER, LINEAR, WILKE]
pure_references = ('ViscosityGases',)
pure_reference_types = (ViscosityGas, )
pure_constants = ('MWs', 'molecular_diameters', 'Stockmayers')
custom_args = pure_constants
def __init__(self, MWs=[], molecular_diameters=[], Stockmayers=[], CASs=[],
ViscosityGases=[], **kwargs):
self.MWs = MWs
self.molecular_diameters = molecular_diameters
self.Stockmayers = Stockmayers
self.CASs = CASs
self.ViscosityGases = ViscosityGases
try:
self.MW_roots = [i**0.5 for i in MWs]
MWs_inv = [1.0/MWi for MWi in MWs]
self.Wilke_t0s, self.Wilke_t1s, self.Wilke_t2s = Wilke_prefactors(MWs)
except:
pass
super().__init__(**kwargs)
def load_all_methods(self):
r'''Method to initialize the object by precomputing any values which
may be used repeatedly and by retrieving mixture-specific variables.
All data are stored as attributes. This method also sets :obj:`Tmin`,
:obj:`Tmax`, and :obj:`all_methods` as a set of methods which should
work to calculate the property.
Called on initialization only. See the source code for the variables at
which the coefficients are stored. The coefficients can safely be
altered once the class is initialized. This method can be called again
to reset the parameters.
'''
methods = [LINEAR]
if none_and_length_check((self.MWs, self.molecular_diameters, self.Stockmayers)):
methods.append(BROKAW)
if none_and_length_check([self.MWs]):
methods.extend([WILKE, HERNING_ZIPPERER])
self.all_methods = all_methods = set(methods)
Tmins = [i.Tmin for i in self.ViscosityGases if i.Tmin]
Tmaxs = [i.Tmax for i in self.ViscosityGases if i.Tmax]
if Tmins:
self.Tmin = max(Tmins)
if Tmaxs:
self.Tmax = max(Tmaxs)
[docs] def calculate(self, T, P, zs, ws, method):
r'''Method to calculate viscosity of a gas mixture at
temperature `T`, pressure `P`, mole fractions `zs` and weight fractions
`ws` with a given method.
This method has no exception handling; see :obj:`mixture_property <thermo.utils.MixtureProperty.mixture_property>`
for that.
Parameters
----------
T : float
Temperature at which to calculate the property, [K]
P : float
Pressure at which to calculate the property, [Pa]
zs : list[float]
Mole fractions of all species in the mixture, [-]
ws : list[float]
Weight fractions of all species in the mixture, [-]
method : str
Name of the method to use
Returns
-------
mu : float
Viscosity of gas mixture, [Pa*s]
'''
if method == HERNING_ZIPPERER:
mus = self.calculate_pures_corrected(T, P, fallback=True)
return Herning_Zipperer(zs, mus, None, self.MW_roots)
elif method == WILKE:
mus = self.calculate_pures_corrected(T, P, fallback=True)
return Wilke_prefactored(zs, mus, self.Wilke_t0s, self.Wilke_t1s, self.Wilke_t2s)
elif method == BROKAW:
mus = self.calculate_pures_corrected(T, P, fallback=True)
return Brokaw(T, zs, mus, self.MWs, self.molecular_diameters, self.Stockmayers)
return super().calculate(T, P, zs, ws, method)
[docs] def test_method_validity(self, T, P, zs, ws, method):
if method in self.all_methods:
return True
return super().test_method_validity(T, P, zs, ws, method)